Segmented Fin-and-Tube Heat Exchanger for Lower Thermal Stress

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Solution Overview

Problem

Conventional fin-and-tube heat exchangers for commercial water heaters with high hot-water supply capability require large, specially manufactured plate fins that increase manufacturing costs and thermal stress, and existing configurations do not adequately address these issues.

Innovation Solution

A fin-and-tube type heat exchanger design where plate fins are arranged side by side in the fore-and-aft direction, with a heat transfer tube passing through both, allowing for smaller plate fins and reducing thermal stress and manufacturing costs, while maintaining heat recovery efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the length of the plate fin in the right-and-left width direction is increased to match the gas combustion area width, then the heat recovery capability is improved, but the manufacturing cost increases and thermal stress increases

Engineering Contradiction:

Improveheat recovery capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The plate fin is divided into multiple fin sections along the width direction, with each section having a manageable length. These sections are arranged side by side to collectively cover the gas combustion area, enabling heat recovery across the full width without requiring each individual fin to be excessively long and expensive to manufacture

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of increasing the length of plate fins in the width direction to cover the combustion area, the invention transitions to arranging multiple fin sections side by side in the width direction. This dimensional reorganization allows the heat exchange surface to span the required area while keeping individual fin dimensions within standard manufacturing ranges

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Loss of energy

If the length of the plate fin in the right-and-left width direction is increased to match the gas combustion area width, then the heat recovery capability is improved, but the thermal stress and reliability issues increase

Engineering Contradiction:

Improveheat recovery capabilityVSAvoidthermal stress resistance

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the geometric parameters of the plate fin by reducing the length of individual fin sections while increasing the number of sections arranged in parallel. This parameter transformation maintains the total heat exchange area while reducing the thermal expansion amount and stress concentration in each individual fin section

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If standard-sized plate fins are used instead of long special-purpose plate fins, then the manufacturing cost is reduced, but the heat recovery capability decreases

Engineering Contradiction:

Improvemanufacturing costVSAvoidheat recovery capability

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

Multiple standard-sized fin sections are merged together in parallel arrangement to form a composite heat exchange structure that covers the entire gas combustion area. The combined heat recovery capability of these standard fins equals or exceeds that of a single long special-purpose fin, while significantly reducing manufacturing costs

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The invention makes the heat exchanger adaptable to different combustion area sizes by using standardized fin sections that can be arranged in various configurations. This universal approach allows the same standard fin components to serve multiple applications with different heat recovery requirements, eliminating the need for custom-long fins

Inventive Principle:

Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The design increases heat recovery from combustion gas without using long plate fins, reduces manufacturing costs, and enhances the durability and reliability of the heat exchanger by minimizing thermal stress and allowing for a more compact size.

Implementation Method 1

a heat transfer tube includes a plurality of straight-type tubular bodies (30) each passing through the plurality of plate fins (1A, 1B) in the fore-and-aft direction

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 2

gas for heating is supplied into the case (2)

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS10094589B2Fin-and-tube type heat exchanger and water heater including the same

Publication Date: 2018.10.09 NORITZ CORP

AI summary

A fin-and-tube type heat exchanger includes: a plurality of plate fins arranged in a case side by side in a fore-and-aft direction of the case; and a heat transfer tube including a plurality of straight-type tubular bodies each passing through these plurality of plate fins. First and second plate fins arranged side by side in the right-and-left width direction of the case are provided as a plurality of plate fins. The heat transfer tube has a connection tubular body connecting the straight-type tubular bodies passing through the first and second plate fins. The heat transfer tube passes through areas in which the first and second plate fins are arranged.